The invention relates to a method for producing low porosity composite castings of 1,3,3-trinitroazetidine (TNAZ).
1,3,3-Trinitroazetidine (TNAZ) is a high density, high energy explosive compound consisting of a 4-membered azetidine ring, with a geminal dinitro substituent in the 3-position and a nitramine substituent in the 1-position: ##STR1##
TNAZ has the advantages of (1) a high level of energy release and (2) a stable low melting point of 101.degree. C., making it a melt castable substitute for TNT with double TNT's energy. However, TNAZ has a high vapor pressure and large volume change upon freezing which results in excessive shrinkage and crystal growth upon solidification. Such recrystallization results in significant defects and porosity which result in unacceptable sensitization of cast charges to shock initiation. Porosity is typically 10-12 percent compared with 2-4 percent usually obtained in TNT casting. The porosity of neat-cast TNAZ charges is excessive for use in secondary explosive applications. Sensitivity levels of from 1-4 kbar have been observed in such charges. This is significantly greater than the reported value of 10.4 kbar observed in fine particle size (10 micron) TNAZ recrystallized from ethanol in a crash precipitation process and pressed to high percents (98%) of theoretical maximum density (TMD).
What is desired is a method for casting TNAZ, whereby excessive vapor pressure is suppressed, charge porosity is reduced and crystal growth rates are such that excessive sensitization to shock initiation of cast TNAZ charges does not result.
It is an object of the present invention to provide a method for casting TNAZ, whereby excessive vapor pressure is suppressed, charge porosity is reduced and crystal growth rates are such that excessive sensitization to shock initiation of cast TNAZ charges does not result.
Other objects and advantages of the present invention will be apparent to those skilled in the art.